INA228: INA228

zaman motamedi

Prodigy 10 points

Part Number: INA228
Other Parts Discussed in Thread: TM4C1233H6PZ, INA226

Using of 96 x INA228 Power monitors with the TM4C1233H6PZ Microcontroller

There are 6 x I2C buses on the Microcontroller. Connecting 16 INA228 power monitors per I2C bus should be possible

Measurements from the Power Monitors are to be transmitted on a USB 2.0 bus to host PC.

Two Questions:

1- Can the Microcontroller handle 96 loads on the I2C buses? (assume 400KHz I2C clock)

2- What would be the maximum number of times each power monitor device can be sampled every second ?

over 3 years ago

0 Mitch M over 3 years ago

TI__Mastermind 19865 points

Hello Zaman,

Thank you for using the TI forum. Here is a link to a thread about the INA228 I2C pin capacitance:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/963065/ina228-q1-i2c-pin-capacitance

If you require an IBIS model, you can use the one from the INA226, as it will be very similar.

I'm sending this thread over to the team that covers the TM4C1233H6PZ to answer your MCU specific questions.

0 Charles Tsai over 3 years ago

TI__Guru**** 167836 points

Hi,

zaman motamedi said:
2- What would be the maximum number of times each power monitor device can be sampled every second ?

The number of I2C devices will be limited by the bus capacitance. For 400kHz, that will be 400pF. Please refer to this app note.

https://www.ti.com/lit/pdf/scpa054#:~:text=The%20I2C%20standard%20specifies%20a,pF%20for%20Fast%20Mode%20Plus.

zaman motamedi said:
2- What would be the maximum number of times each power monitor device can be sampled every second ?

I think you can do a rough calculation. Reading the INA228 datasheet, you need one secondary address byte followed by the number of bytes in the register you want to read. Suppose you are reading a 3-byte register, you will need a total of 4 frames to read a 24-bit (3bytes) register. Each frame is 9 bit (including the ACK). Four frames will take 36 bits. If you divide 400k by 36 is about 11.11k times that you will be able to read one register in one second. If you need to read x number of registers, I think you can calculate that by dividing 11.11k by x.

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INA228: INA228